The present invention relates to fifth wheel, and in particular to a lightweight narrow-span fifth wheel.
FIG. 2 illustrates a prior construction of a tractor frame and mounting system 10 for tractor/trailers. The prior construction tractor frame and mounting system 10 includes a pair of parallel frame rails 12 spaced 34 inches apart that support a suspension 14, a drive train (not shown) and a coupling apparatus 16 for connecting a trailer to the tractor. FIG. 2 illustrates truncated frame rails 12. Therefore, while the frame rails 12 are illustrated as ending under a deck 17, the rails 12 continue in front of the deck 17 and extend under the cab of the tractor and support the cab and the engine of the tractor. The coupling apparatus 16 includes a fifth wheel hitch 20 (see also FIG. 1). The coupling apparatus 16 further includes a mounting bracket and base plate assembly 18 configured to connect the fifth wheel hitch 20 to the frame rails 12. The mounting bracket and base plate assembly 18 includes a pair of oppositely facing, inverted L-shaped brackets 22 connected to ends of a base plate 24. The base plate 24 is a planar sheet of steel and includes a pair of mounting brackets 26 extending upwardly from a top surface of the base plate 24. The coupling apparatus 16 is connected to the frame rails 12 by placing ends of the base plate 24 over the top surface of the frame rails 12 and by inserting fasteners (not shown) through vertical legs of the L-shaped brackets 22 and into outside faces of the frame rails 12. Therefore, the L-shaped brackets 22 assist in connecting the coupling apparatus 16 to the frame rails 12 of the tractor. Each mounting bracket 26 of the mounting bracket and base plate assembly 18 includes an elongated aperture 28 therein configured to accept conventional attachment structure (not shown) for connecting the fifth wheel hitch 20 to the base plate 24. The elongated apertures 28 are co-linear and the distance between the center of each aperture 28 is typically 30 inches. The fifth wheel hitch 20 is configured to accept a pin of a trailer to connect the trailer to the tractor. The mounting brackets 26 are also positioned over the frame rails 12. Since the fifth wheel hitch 20 accepts the pin within a center opening 30, the primary load of the trailer rests on the top surface of the fifth wheel hitch 20. Therefore, the primary load of the trailer is on the mounting bracket and base plate 24 at the center of the base plate 24. The load from the trailer is transferred to the attachment points of the mounting bracket and base plate assembly 18 to the frame rails 12 through heavy ribs and other structure that act as a beam.
The prior construction fifth wheel hitch 20 (FIG. 1) includes a hitch plate 11 defining the throat 30 for receiving a kingpin. The hitch plate 11 has a bottom face 15 and has a thickness of about 0.45 inches. Back ribs 27 extend from the bottom face 15 of the hitch plate 11 and have a thickness of about 0.625 inches. A peripheral flange 19 extends from a periphery of the bottom face 15 of the hitch plate 11 and is connected to ends of the back ribs 27. A main rib 21 extends from the bottom face 15 of the hitch plate 11 between the back ribs 27 and a portion of the peripheral flange 19, with the main rib 21 being connected to ends 23 of the peripheral flange 25. The main rib 21 has a thickness of about 0.75 inches. Skirts 29 extend from the hitch plate 11 adjacent the back rib 27 and define a tapered mouth 31 leading to the throat 30. Skirt ribs 33 are positioned on the skirts 29 and have a thickness of about 0.45 inches. A mounting rib 35 is located interior of the peripheral flange 19 on each side of the throat 30. The mounting brackets 26 are connected to the fifth wheel hitch 20 by inserting the mounting brackets into a space 37 between the mounting rib 35 and the peripheral flange 19. A mounting pin (not shown) is inserted through aligned apertures in the peripheral flange 19 and the mounting rib 35 to connect the fifth wheel hitch 20 to the mounting brackets and the tractor.
The prior construction of the tractor frame and mounting system 10 for tractor/trailers typically has frame rails 12 with a 34 inch spacing between the center of the apertures 28 in the mounting brackets 26 for accommodating the weight load of the engine and the cab of the tractor. However, the 34 inch spacing of the frame rails 12 requires the fifth wheel hitch 20 to include heavy ribs for supporting the weight of the trailer in order to span the 34 inch distance and to transfer the load placed on the fifth wheel hitch 20 to the mounting brackets 26. The prior construction of the tractor frame and mounting system 10 includes numerous mounting brackets, angle brackets, base plates, slide plates, etc. which add to the weight of the tractor frame and mounting system 10 in addition to installation time.
Accordingly, a fifth wheel and mounting system solving the aforementioned disadvantages and having the aforementioned advantages is desired.